Our investigation during this grant period presents a quantitative analysis of the asymmetric transmembrane lipid packing geometry in egg phosphatidylcholine vesicles. The analysis uses hydrodynamic and nuclear magnetic resonance data obtained for homogeneous egg phosphatidylcholine vesicles and demonstrates that the average area per lipid head group and effective length of the lipid are greater on the outer monolayer than on the inner monolayer of the egg phosphatidylcholine vesicle. Results also indicate that the bilayer of the egg phosphatidylcholine vesicle has an asymmetrical interface through its center.